Always hide hot spot shapes

Hi,
I'm trying to design a task where participants can cross out/mark the letters from the image by selecting it. So I used the hot spot function and tried to map each letter with a hot spot. But currently, it is slowing down the process because there are too many hot spots on a single page. So I'm wondering if there is anyway to always hide the hot spot shapes, so that the participants won't be able to see the hot spots and will assume that all letters are markable rather than scanning the text with their mouse to simply click whichever letters are clickable if I decided to only use hot spots on letters I want them to select.